Production of phenol aldehyde resins



Patented Apr. 18, 1950 2,504,100 lCE PRODUCTION OF PHENOL ALDmYDE RESIN 8 Charles J. Hank and Darwin E. Badertscher. Woodbury, N. 3., assignors to Socony-Vacuum Oil Company, Incorporated, a corporation New York No Drawing. Application September 19, 1947, Serial No. 775,158

10 Claims. (Cl. 260-51) This invention has to do with the production of phenol-formaldehyde type resins.

Resins of the phenol-aldehyde type, that is, those obtained by the condensation of a phenol and an aldehyde, are well known to those familiar with the art. Numerous procedures have been proposed for the preparation of these resins and, in general, catalytic procedures have beenmore successful than the non-catalytic. Various tacids, bases and salts have all been credited with the ability to facilitate the condensation of phenol and formaldehyde, and thereby produce fresins of diflerent degrees of color, toughness, stability, etc., as well as different degrees of solub ty in acids, bases and solvents. Unless great are is exercised in their preparation, however. t e resins of this type tend to be dark in'color an relatively unstable to the action of light a d air. The decolorization of a dark resin of this pe, or the precautions necessary for the preparat on of a light-colored resin, appreciably increas s the cost of the resin.

This invention is predicated upon th discovery that the condensation of pheno with formaldehyde, and more broadly the con ensation of a hydroxylated aromatic hydrocarbon with an aldehyde, is aided by boron triflfuoride and complexes of boron trifluoride. The iresins obtained by such a condensation are cle r and light-colored, and as such are more desirable than those obtained with other condensation "agents.

The condensation contemplated herein is adapted for resiniflcation of hydroxyaromatic compounds with all saturated aliphatic and aromatic aldehydes, typical of which are formaldehyde, acetaldehyde, butylaldehyde, benzaldehyde, etc., in the presence of BF: or a BB5 complex. Preference is given to the aliphatic aldehydes and particularly preferred herein is formaldehyde.

As aforesaid, hydroxylated aromatic hydrocarbons condense. with the foregoing aldehydes in the presence of boron trifluoride or a complex of said fluoride. Monoand poly-hydroxylated, monoor polycyclic aromatic hydrocarbons are contemplated herein, representative of which are the following: phenol, cresols, p-tertiary butyl phenol, p-tertiary amyl phenol, resorcinol, alpha-and beta-naphthols, monoand polyhydroxy methyl naphthalenes, monoand polyhydroxy polymethyl naphthalenes, etc. Phenol is particularly preferred of such compounds. It is to be understood, however, that hydroxylatedand hydrogenated-aromatic hydrocarbons, such as cyclohexanol, are also contemplated herein.

Boron trifluoride and complexes of said fluoride which are dissociated at the reaction temperature are, as aforesaid, the condensation 2 Included among such complexes are the etherates represented by the general formula ROR'BFa, wherein Rand R are the same or different organic radicals: examples of such etherates are those of dimethyl ether, diethyl ether, methyl amyl ether, methyl phenyl ether, ethyl phenyl ether, etc. Complexes of acid halides and BF: are also contemplated, such complexes being represented by the general formula RCOX-BFa, wherein R is an organic radical and X is a halogen atom; typical of such complexes is acetyl-chloride BFa. The ester *BF: complexes comprise still another group, being represented by RCOOlV-BFa, wherein R. and R are the same or different organic radicals, as typified by methyl formate -BF'a, ethyl formate -BF3, methyl acetate -BF:, ethyl acetate -BF3, methyl benzoate BF: and HOCHzCOOCHa-BFa. Representative of the nitrogen-containing compounds which form complexes with boron trifiuoride and which may be employed are complexes such as are formed with the aromatic amines aniline, toluidine, etc. However, it is preferred to employ complexes of BF: and primary amines rather than complexes of BF; and secondary amines such as diethyl amine or BF; and tertiary amines such as pyridine. contemplated also are complexes of the type (RO'BF'3) -H+, wherein R is an organic radical, such being obtained by reacting alcohols, as methyl and ethyl alcohols, with BFa.

Of the foregoing condensation agents, however, boron fluoride and its diethyl etherate (HsCzOCzHsBFs) are particularly preferred.

The process contemplated herein for the production of phenol-formaldehyde type resins involves the following: phenol and formaldehyde, for example, are allowed to react in the presence of gaseous boron trifluoride or a boron trifluoride complex, which is in the liquid state. Formaldehyde may be used in the gaseous phase, aqueous solution or solid phase. The amount of boron triiiuoride used may be varied considerably; however, from about 0.01 per cent to about 10 per cent by weight of the reactants is preferred.

.- Similarly, the amount of boron trifiuoride complex, such as an etherate, may be varied considerably, preferred amounts being from about 0.02 per cent to about 20 per cent by weight of the reactants. The reaction or condensation is preferably carried out at temperatures from about 0 C. to about C., particularly irom' about 40 C. to about 100 (2.; however, initial temperatures below about 0 C.-may also be used as may temperatures up to the boiling point of phenol (182 0.). In general, it is preferred to use a temperature high enough to insure a liquid solution of the reactants, yet low enough to obviate an instantaneous reaction attended by the evolution of an excessive amount of heat. This will be explained in more detail by the typical examples shown hereinafter. reaction mixture during the course of the reaction or condensation. The reaction or condensation product is usually water-washed in order to remove the catalyst and any water-soluble products formed in the reaction. If the quantity of catalyst is not large, however, the water-washing operation may be omitted; in which case a lower temperature can be used during the setting operation, in view of the catalyst present in the product. It is to be noted that while white or colorless thermosetting resins are produced when phenol and formaldehyde are the reactants, the resins obtained when using other reactants, al-

, though colored, are of such light color that the resins can be readily pigmented to provide thermoset resins in pastel shades. Thus, it is now possible economically to produce phenol-formaldehyde type resins from which thermoset products in white to pastelshades can be produced. The process requires the use of. only one catalyst and makes it possible to secure products having all the advantages of prior art phenol-formaldehyde type resins plus the additional advantage of light to white color.

Although the proportions ofthe reactants, aldehyde and hydroxylated hydroaromatic hydrocarbon, may be varied over a wide range in order to obtain resins with varying properties, it is preferred that a sllghtlylarger molar quantity of aldehyde than said aromatic hydrocarbon be used. For example, to obtain a preferred phenol-formaldehyde resin, a ratio of about '7 moles of formaldehyde to about 6 moles of phenol is used. The following examples serve to illustrate the new process and the resins obtained therewith.

Example I A mixture of 100 grams of phenol and 100 grams of aqueous formaldehyde (3'? per cent) were placed in a beaker and gaseous BF: was slowly bubbled into the reactants at about 30 cos. per hour. After about 15 minutes, an exothermic reaction commenced and the water present therein began to boil. The reaction mixture was then divided into two portions. Portion (a) was allowed to stand without any further addition of 1313's, and it gradually cooled to room temperature whereupon a white, opaque, tafiy-like material was obtained after 5 to 6 hours. Portion (1)) was maintained at 100C. with BF: passed therethrough for 30 minutes. white, opaque, taffy-like substancewas obtained in less than one hour.

The products obtained in (a) and (b) were combined and water-washed, being worked by hand under cold water. After so treating for 10-15 minutes, the product became considerably harder. The water-washed product was heated for about minutes at 150? 0., whereupon it melted. On cooling, it set to a hard, clear, lightcolored, brittle-resin.

Example II A 100 gram portion of phenol was melted in It is beneficial to stir the I into two portions. Portion (a) was placed in another beaker and brought to the boiling point of water, at which point the beaker was no longer heated. Reaction had started and so much heat was evolved that extremely vigorous boiling continued even after the beaker was no longer heated. A white, opaque, taflfy-like product was formed in 10-15 minutes. This product was water-washed as described in Example I, and the product obtained after minutes was an extremely hard, clear, light-colored resin.

Portion (b) was allowed to stand at room temperature (about 25 C.) with no further addition of BFa. In 72 hours, a white,' opaque, tally-like product was formed.

Example. III

The temperature was reduced to about C.

A similar a beaker and a slow stream of gaseous BF: was

bubbled therethrough. With rapid mechanical agitation and continued addition of BFa, grams of formaldehyde solution (3'7 percent) were added dropwise over a 30 minute interval. No sudden reaction or temperature change occurred, the average temperature being 50 C. and

and gaseous BF: was indected into the mixture. Practically instantaneous reaction occurred, the

mixture boiling vigorously. The Jet, through the instantaneous condensation when the catato a clear, light-colored thermo-setting resin, as

in Examples I and II.

? Example IV Twenty-five (25) grams of phenol were dissolved ;in the same weight of 37 per cent formaldehyde solution and 1 ml. of (H5C2)zO-BFa was added thereto. Apparently no immediate reaction took place, but the solution became cloudy after several minutes. After one hour, a definite white solid began to separate. On standing overnight, the white mass had coagulated to a white, tafiy-like solid. The product was worked up mechanically, whereupon it became harder and lighter colored. After standing 48 hours at room temperature (about 25 0.), the product was quite brittle, the edge of a fracture exhibiting a glassy appearance.

Example V thickened considerably but was still not resini-' fied. Another 15 grams of formaldehyde solution were added to react with any excess phenol that might be present. After 48 hours, a. lightcolored, rubber-like mass was obtained. When this mass was then heated to 100 C. for 20 minutes, further reaction occurred and, on cooling, a clear light-colored, hard, brittle resin was obtained. v

Example VI One (1) ml. of (HsCzhO-BF: was added to 25 grams of phenol and 25 grams of 37% formaldehyde solution. No reaction was apparent for one hour and the reaction mixture was then heated to about 70 C., at which point heating was discontinued- After a minute or two, a vigorous exothermic reaction took place, the temperature being spontaneously increased to about 100 C. The greater portion of the product became solid at this time and the liquid portion was decanted. The solid portion was heated to 90 C. for several minutes and, on cooling, a clear, light-colored, hard, brittle resin was obtained.

To further illustrate the broad scope of the present invention various other hydroxy aromatic compounds were reacted with various other aldehydes in the presence of other boron trifluoride complexes under substantially the same reaction conditions as set forth hereinbefore. All of the resins so produced were thermosetting and either white in color or of such light color that they could be readily pigmented in the conventional manner to provide resinous masses in pastel shades. v

The present application is a continuation-ins part of the application for United States Letters Patent Serial No. 505,966 flied October 12, 1943 in the names of Charles J. Plank and Darwin E. Badertscher and now abandoned.

We claim:

1. A process for preparing light colored to white thermosetting resins of the phenol-aldehyde type which comprises condensing only phenol and formaldehyde in the molar proportions of 6:7 in the presence of boron trifluoride at temperatures of C. to 182 C., whereby a phenol-formaldehyde resin is obtained which after melting cools to a light colored to white thermosetting resin. v

2. The process as described and set forth in claim 1 wherein condensation of said phenol and said formaldehyde takes place at temperatures of 0 C. to 100 C.

3. A process for preparing light colored to white thermo-setting resins of the phenol-aldehyde type in one step which comprises condensing in the presence of boron trifluoride at 0 C. to 182 C. only a phenolic compound selected from the group consisting of phenol, mono-cyclic phenol having only an alkyl group having not more than five car- Color oi Prod- Time to Thermo- Ex. No. Reaction Mixture not set at 150 Q VII 100g phtenol, 100 g. 36% aqueous formalin, ml.; of BF; White 3-6min.

ct era e. VIII 100 g. pheiiol, 100 g. 36% aqueous formalin, 5 ml. of BF; do 5min,

met ano Ix 100 g. phenol, 100 g. 367 aqueous formalin, 5 g. of BF; anilinelight red 80 min. x lilotg. ptcresol, 100 g. xe% aqueous lormalimo ml.- of BF: lighttan 30 min.

e era e. x1 100 ghp-crlesol, 100 g. 36%.aqneous lormal.in,5,-'ml. of BF; dn 30 m,

met ano XII 1003i p-uflamyllphenol, 100 g. 36% aqueous formalim ii mL of yellow tacky 4 min.

a me ano XIII 100 giho-crfsol, 100 g. 36% aqueous formallu,5 ml.- of BF; pale pink aomln,

me ano XIV (1)3 alphg-naphthol, 100 g. 36% aqueous i'ormalln, 5 ml. of light red 1 min,

a me ano XV 100mg; retsorcinol, 100 g. 36% aqueous formalin, 5 ml, of BF; red brittle already therm t,

e era e. XVI- gb resorcinol,25 g. 36% aqueous formalin, 0.001 ml. of BF; do. Do.'

at crate. E XVII- 25 g. henol, 25 g. benzaidehyde, 2 ml. of BF; methanol d tacky mm. XV 94 g. phenol, 44 g. aeetaldehyde, 5 ml. of BF; methanol Einkish to tan. 5 min. XIX".-- 25 g. ghenoi, 25 g. 36% aqueous, formalin, 1.5 ml. of B Fu acetic ght gray 1 min,

aci 1 It is to be noted that the present process provides another means for producing thermoset resins in a one-stage process. That is to say, the phenol and aldehyde are reacted in the mole ratio of about 1 mole of phenolic compound to about 0.88 to about 2 moles of aldehyde (as listed in the foregoing tabulation) in the presence of BF: either in the form of gaseous BF: or of a complex as defined hereinbefore and the reaction interrupted when the resin is in the A or B stage. Water is then removed from the reaction mixture by decantation and/or by heating the reaction mixture under a vacuum. The resin is then mixed with fillers and molded to obtain a thermoset molded product.

It is to be understood that the foregoing examples are illustrative only and that this invention is not limited thereto, rather the invention is to be broadly construed in the light of the language of the appended claims and as broadly as the prior art will permit. Thus, although the phenol and the aldehyde in the illustrative examples were reacted in a molor ratio of about 1 to 1.2, i. e. in the presence of a slight excess of aldehyde, it is to be understood that the molar ratio of hydroxylated aromatic compound to aldehyde can be varied within the limits of 1:2 to 2:1; or broadly, within those limits employed in the art heretofore.

bon atoms attached to the nucleus in one of the ortho and para positions and unsubstituted hydroxylated polycyclic aromatic compounds having not more than two hydroxyl groups attached to the aromatic nucleus and an aldehyde selected from the group consisting of unsubstituted saturated aliphatic aldehydes and unsubstituted aromatic aldehydes in the ratio of 1 mole of phenolic compound to about 0.88 to about 2 moles oi aldehyde.

4. A process for preparing light colored to white thermo-setting resins of the phenol-aldehyde type in one step, which comprises condensing in the presence of boron trifluoride at 0 C. to 182 C. only an unsubstituted polyhydric phenol and an aldehyde selected from the group consisting of unsubstituted saturated aliphatic aldehydes and unsubstituted aromatic aldehydes in the ratio of 1 mole of said polyhydric phenol to about 0.88 to about 2 moles of said aldehyde.

5. A process for preparing light colored to white thermo-setting resins of the phenol-aldehyde type in one step, which comprises condensing in the presence of boron trifluoride at 0 C. to 182 C. only an unsubstituted hydroxylated polycyclic aromatic compound having the hydroxyl group attached to the aromatic nucleus and an aldehyde selected from the group consisting of unsubstituted saturated aliphatic aldehydes and unsubstituted aromatic aldehydes in the ratio of 1; mole of said hydroxylated polycyclic aromatic,

compound to about 0.88 to about 2 moles of said aldehyde.

6. A process for preparing a thermo-setting resin in one step which comprises condensing in the presence of boron trifluoride at 0 C. to 182 C. only'phenol and benzaldehyde in the ratio of 1 mole of phenol to about 0.88 mole oi: benzaldehyde.

I. A process for preparing a thermo-setting the presence oi boron trifluoride at 0 C. to 182 C. only phenol and formaldehyde in the molal ratio of 1: about 0.88 to about 2.

8. A process for preparing a thermo-setting resin inone step which comprises condensing 1n the presence of boron trifluorlde at 0 C. to 182 C. only resorcinol and formaldehyde in the molal ratio of 1:1.32.

8. A process for preparing a thermo-setting resin in one step which comprises condensing in the presence of boron trifluoride at 0 C. to 182 5 the presence of boron trifluoride at 0 C. to 182 G. only alpha naphthol and formaldehyde in the molai ratio oi 1:1.11.

CHARLEE-LPLANK.

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resin in one step which comprises condensing in 4 REFERENCES CITED .Thexiollowin'g references are of record in the 15 iile oithlszpatent:

. UNITED STATES PATENTS Number- Name Date 2,237,634 Rosen Apr. 8. 1941 FOREIGN PATENTS 20 Number Country i Date 106,686 France Dec. 14,- 1909 493,082 Great. Britain Oct. 3, 193a 

1. A PROCESS FOR PREPARING LIGHT COLORED TO WHITE THERMOSETTING RESINS OF THE PHENOL-ALDEHYDE TYPE WHICH COMPRISES CONDENSING ONLY PHENOL AND FORMALDEHYDE IN THE MOLAR PROPORTIONS OF 6:7 IN THE PRESENCE OF BORON TRIFLUORIDE AT TEMPERATURES OF 0*C. TO 182*C., WHEREBY A PHENOL-FORMALDEHYDE RESIN IS OBTAINED WHICH AFTER MELTING COOLS TO A LIGHT COLORED TO WHITE THERMOSETTING RESIN. 